Most software applications intended for producing documents have been released for sale to the public in an initial version, e.g., version 1.0, and over time, successively newer versions have been developed and made available for purchase. Each new version typically incrementally adds functionality and features. Occasionally, the added features in a new version require that changes be made in the format in which a document is saved, compared to the format used for such documents an earlier version of the program. Also, because editing or even accessing the new features or functionality in a document will often only be possible using the new version of the software code, a document that includes any of the new features or functionality may not be entirely backwards compatible with earlier versions of the software program that was used to create or edit the document.
Another common compatibility issue arises if the document was created using a software application written to run on one computing platform (i.e., on a computer using a specific type of processor and/or operating system), and the document is to be accessed using a different type of processor/operating system. Although the document may be distributed to someone who is using a similar software program that was designed to run on a different computing platform and/or operating system, the functionality and feature sets of versions of the program written for different computing platforms and/or operating systems may be different. For example, Microsoft Corporation sells the OFFICE™ Suite of software applications, which includes WORD™ word processing and EXCEL™ spreadsheet programs, for both the WINDOWS™ operating system and the APPLE™ operating system that is used on Apple MACINTOSH™ computers. However, the functionality and feature sets in the two products written for use on the different platforms and operating systems are somewhat different, and the release of a new version written for use on one computing platform and operating system may not coincide with a corresponding release of a new version written for use on the other computing platform and operating system.
Sometimes, compatibility issues can arise due to differences in related software that may be available on one user's computer, but not on another, even though the computing platforms and operating systems employed by the two users are generally identical. A good example of this type of compatibility problem is the effect on the appearance of a document when a specific font is employed by the creator or editor of the document that is distributed to another who is using a computer on which that font is not installed. While a substitution font may be applied to address this issue, the look of a document can be substantially altered if a font used in its creation or in its edited form is unavailable on the computer used by another person who is accessing the document for display or printing.
Clearly, although it may not be possible to ensure that all documents created using a software program are compatible when accessed with all versions of the software program, it would be desirable for a user who is creating or editing a document to be provided a warning of any potential compatibility problems. Thus warned, a user might elect to change the document to eliminate the cause of incompatibility, or take other appropriate steps to address the problem. Of course, the warning might be freely disregarded if the user is certain that the incompatible software or computer platform will not be used by others who will be accessing the document. Nevertheless, by providing a user with a warning of potential compatibility problems in regard to documents that are being created or edited, the user would have the option, where possible, to correct the potential problem. The fix might be as simple as embedding a specific font in the document, if the user knows that the font is not likely to be available on the computers of others interested in accessing and printing the document.